No, an exporter is not required to "register" in relation to the AGOA legislation in order to take advantage of its benefits when exporting goods to the US.

However, each country has different rules and regulations and many countries require that an exporter be registered for export purposes (this is unrelated to AGOA per se) with local customs or revenue authorities. Often this also involves receiving a unique exporter authorization number. These are national country-specific measures and different from country to country: it is advisable to contact the customs or revenue authorities in the home country to see what registration measures and related formalities may be required.

What is however important to bear in mind is that while the exporter is not required to register as a 'participant' under the AGOA program,

(a) the country must be a current AGOA beneficiary country (see relevant section here),

(b) the product(s) must be AGOA-eligible, and

(c) the product must originate in an African AGOA beneficiary country in accordance with AGOA’s Rules of Origin provisions.